Reel control



May '12 1942.

D. l. BOHN REEL CONTROL Filed April 15, 1939 mvsm'ox DONALD I. Bot-1N.

ATTORNEY.

Patented May 12, 1942 UNITED STATESPATENT OFFICE mesne assignments,facturing Company, ration of Delaware to Allis-Chalmers Manu- Milwaukee,Wis., a corpo- Application April 15, 1939, Serial No. 268,106

9 Claims.

This invention relates to mechanisms for tension unwinding and rewindingof strip material and the like, which may be used in conjunction withmechanisms for rolling, processing, or otherwise feeding strip materialand the like. It

relates particularly to electrical control systems for reel mechanismscapable of maintaining constant tension on material delivered to or froma rolling'mill, which employ photo-electric torquecontrolling meansresponsive to change in radius of material on a drum or reel. While theinvention is particularly adapted to controlling strip material reels itwill be apparent that wire spools and the like could be controlled bythe apparatus disclosed herein, but reference is made particularly tostrip reel mechanisms.

It is recognized in rolling practice that the speed of rolling stripmaterial may be greatly increased, and the quality of the product may bematerially improved, when a predetermined tension is exerted upon thestrip material before, after, or both before and after it is passedthrough a rolling mill. Coil unwind and rewind mechanisms may beconveniently used for applying tension to the material by applyingsubstantial resistive forces or motive forces, respectively, thereto. Inother words, the back torque on an unwinding coil or reel may becontrolled to exert and maintain tension on the material before itenters a mill; or drive torque on a rewinding coil or reel may becontrolled to exert and maintain tension on the strip material after itpasses from a mill. Since the increment of torque necessary to overcomefrictional and bending losses, to effect uncoiling or recoiling of stripmaterial, is small compared to the torque required to exert'asubstantial tension in the material, the forces necessary to exert suchincrement of torque may be disregarded for purposes of this disclosure,though they may be compensated for in the apparatus disclosed.

For further reasons known in the art, it is desirable to apply thetension at a constant predetermined value and to maintain the tensionconstant at all speeds independently of the driving means for the millor other apparatus through which the strip material is rolled,processed, or otherwise fed. In order to exert constant tension on thematerial delivered to or from a rolling mill, the torque developed bythe unwind resisting apparatus, or by the rewind driving apparatus, mustbe progressively changed to compensate for the change in radius of thecoil of material. The decreasing radius of an unwinding coil may bereferred to as run-down, and

the increasing radius of a rewinding coil may be, and commonly is,referred to as build-up.

Early recognition of the problem of compensating for build-up on arewind reel is found in prior art disclosing mechanical means employingclutches, slip-gears, brakes, and the like, for adjusting rewind drivetorque. Also, certain electrically controlled systems have beendeveloped to supplant the mechanical devices. The electricallycontrolled systems have usually operated on a common fundamentalprinciple, in

that the rewind motor has been coordinated with the mill motor. Theseveral types of prior, rewind torque-controlling devices are referredto in my earlier Patent No. 2,043,208, patented June 2, 1936, andentitled Motor control system for coiling mechanisms," which disclosesa- .urther improvement in electrical control devices obviating thenecessity of employing auxiliary equipment to supplement the powerdeveloped by the mill motor for driving a coiler motor.

The present invention obviates the low degree of accuracy, and sluggishoperation resulting from wear, in mechanical control means. The presentinvention further is an improvement over former electrical controlmeans, and is an improvement over my prior patent, firstly, in beingoperable independently of the mill drive and entirely independently ofthe speed of the material, and secondly, in being operable in directresponse to change in coil radius.-

This invention is particularly concerned with a photo-electric means,sensitive to change in radius of the material on a reel, for operating ameans for varying back torque or drive torque on the reel. The device ofthe present invention has at least two particular advantages overmechanical devices, such as have been used in the past, for respondingto change in radius of the material on the reel: First, no roller orother mechanical element need touch the strip material. It follows,therefore, that marking or scratching of the strip material beingprocessed, especially noticeable on light metals such as aluminum, isentirely avoided. Second, the photo-electric device and associated meansmay be located out of the way of the operator, as by placing it beneaththe reel or coil, permitting the torque-controlling system operatedbyjhephoto-electric device to be located in any convenient place removed fromthe reel or coil.

The present invention is, then, directed toward overcoming theundesirable factors inherent in formerly known unwind or rewindmechanisms. It has for an object the provision of photo-electric meansfor controlling back torque or drive torque of such mechanisms, wherebyany predetermined constant tension may be maintained on the materialbeing processed. Another object is to maintain constant tension on thematerial being processed, regardless of speed or change in radius of thematerial on the reel.

Further objects of this invention are to make it possible topredetermine the tension to be applied to the material, to employotherwise constant torque resisting means or driving means for the reel,to eifect variation in the torque in proportion to change in coilradius, to register or indicate changes in coil radius without marringthe material, and to effect translation of indications of change in coilradius into impulses for varying back or drive torque.

These and various other objects, as well as other novel features andadvantages of the invention, will become apparent in considering thefollowing detailed description of preferred embodiments of theinvention, set forth in conjunction with the accompanying drawing whichrepresents, diagrammatically, an arrangement of the improved constanttension, photo-electric control system for a strip material reelmechanism.

Since a description of this invention as applied to control of a stripmaterial rewind drive is exemplary of the novel features, reference willfirst be made to such an apparatus. As will appear throughout thisspecification, however, a rewind drive control apparatus may be adaptedto function as an unwind resistive control apparatus without anyfundamental changes in the system; and, as will be evident to oneskilled in the art, the principle of operation of the rewind mechanismfirst disclosed will remain substantially the same, when converted to orused as an unwind mechanism. When used as an unwind control mechanism,the power fiow, in what is presently described in the immediatelyfollowing embodiment of the invention as a reel driving motor, agenerator, and a prime mover, would be reversed. The motor and the primemover would act as, or be replaced by, generators; and the generatorwould act as, or be replaced by, a motor.

The drawing may be considered illustrative of the invention as appliedto the control of a rewind reel or coiler mechanism such as is employedin conjunction with a rolling mill. The apparatus shown comprises arolling mill or other suitable feeding device employing a pair of rollsI and II, which may or may not be driven as desired. The strip material12, or other stock to be coiled after passing through rolls Ill and I i,is shown engaged on the discharge side of the rolling mill upon a coilerreel l3 of any suitable construction. An initial turn or coil H of thestrip material I 2 is shown wound on coiler l3. Coiler I! hasmechanically coupled thereto a suitable driving motor l5, preferably afully compensated, shunt excited, direct current motor.

The preferred characteristics of the coiler drive motor I! are set forthpresently for clarity in describing the invention. The shunt excited D.C. motor I5 is capable of exerting a torque proportional to its armaturecurrent and to its ellective field flux. In the embodiment -of theinvention disclosed, the armature current is riaintained at a, constantvalue by a current regulator system in a loop circuit hereinafterdescribed. Since the armature current may be maintained constant, thetorque of the coiler drive motor I 5 may be made dependent upon itsfield strength. Control of field strength may be conveniently adjustedby means of a multiple position rheostat inserted in the circuit of thecoiler motor field, the operation of which by a photo-electric deviceand associated means is hereinafter disclosed in this specification.

The tension on the material I! is directly pro portional to the torqueof the drive motor l5 and inversely proportional to the radius of thecoil I4. Therefore, with a constant armature current, tension becomes afunction of field strength and coil radius; and the former may beprogressively adjusted to compensate for progressive change in thelatter.

Control of coiler drive torque by maintaining constant armature current,and by varying the field strength, may be independent of the mill speedor of the strip material speed; and the tension on the material may bemaintained at a constant value regardless of its speed.

Coiler drive motor I5 is excited by a field winding l6. Current issupplied to field winding I 6 through conductors l1 and I8; and a fieldrheo- P stat I9 is located in circuit with conductor ll for varying thecurrent supplied to field winding l6, thus providing a means forcontrolling the excitation of coiler motor l5. Conductors l1 and I 8connect with power mains L1 and L2, respectively, which may be, forexample, 230 volt, direct current constant potential mains. A rotatablearm 20 on rheostat i8 is adapted to be moved around the contact portionsof rheostat I! for changing the resistance in circuit with field IS. Therheostat I9 is designed so that equal increments of rotational movementsof arm 20 inserts in, or withdraws from, circuit with field I6 suchincrements of resistance as will cause equal changes in the torquedeveloped by motor l5. In other words, rheostat I9 is pref erablyconstructed in accordance with the torque characteristics of motor l5 soas to give a straigt-line relation between angular movement of arm 20and change in torque of motor I5. The operation of rheostat arm 20 onrheostat I! by a photo-electric device and associated electri-' calmeans is described following a disclosure of a means for supplyingconstant armature current to motor I 5.

Armature current may be supplied to coiler motor l5 by any convenientsystem of adjustable constant current supply. A typical constant currentsupply system is illustrated diagrammatically in the drawing andcomprises a generator 2! in a loop circuit with the motor I 5, thegenerator 2| being driven through a suitable mechanical coupling with aprime mover 22. Prime mover 12 may be any convenient approximatelyconstant speed type of motor, and is dissociated from the mill drivemotor; it is shown in the drawing as a three-phase alternating currentinduction motor operated ofi three-phasev power mains L3, L4, and L5 ofsuitable potential. Conductors 28 and 24 connect the armatures ofgenerator 2| and motor l5, respectively, in a locp circuit. Inserted incircuit with conductor 23 is an ammeter 25, which may be employed forchecking the loop circuit current value, whereby the operator maydetermine whether or not the current is remaining constant and whetherit is at a proper value for any predetermined constant tension to beapplied to the strip material, as a check upon a current regulatorrheostat setting to be hereinafter described. Ammeter 25 may becalibrated to read in units of tension aasaoac 3 directly, if desired.In series with conductor 23, there is a shunt 28, across which a coil 33is connected, as will be described, for a current regulator identifiedgenerally by the reference numeral 21.

The excitation of generator 2| is produced by a field winding 28 excitedand controlled in conjunction with the current regulator 21. A resister29 is adapted to be connected across the direct current mains Li and Lathrough a doublepole, double-throw switch 30, the central terminals ofwhich connect to mains L1 and L2 through conductors I32 and 32,respectively. One connection for field 28 is normally made to main L: bymeans of a conductor 9|, through conductor 32 connected to main L2. Thesecond connection for field 28 is normally by means of a conductor |3|connecting to a potentiometer tap 33 on resistor 29 (through all, part,or none of the resistance of which the exciting current for field 28must pass), knife switch 38, and.

conductor |32. Switch 30 is shown closed in its normal position foroperation of the mechanism as a rewind. The second position of knifeswitch 30, shown dotted, is adapted to reverse the connection toresistor 29 without reversing the connections to field 28, for operationof the mechanism as an unwind. The latter change becomes necessary toaccommodate the proper action of regulator 21 to the change inelectrical power flow when the mechanism is used as an unwind. Currentregulator 21 operates to control the position of potentiometer tap 33along the resistor 29, the above-described field connection beingreferred to as a potentiometer connection.

Current regulator 21 comprises the operating coil 33 connecting acrossshunt 26 through lead wires 35 and 36. Inserted in circuit with leadwire 38 to coil 33 is an adjustable rheostat 31 having a control arm 38,by means of which the resistance in circuit with coil 33 may becontrolled. Coil 33 is operable to move a magnetic plunger 39mechanically connected to the potentiometer tap 33 on resistor 29.Plunger 39 may be spring resisted or'merely adapted to resist the forceof coil 33 by its own weight, such device being known in the art and,therefore, not necessitating further description here. Rheostat controlarm 39 may be set at any predetermined p'osition, thereby controllingthe relative strength of coil 33 and adapting it to adjust the positionof the tap 33 on resistor 29 in response to any tendency toward changein loop circuit current so that the strength of field 28 may be adjustedto maintain constant current in the loop circuit comprising generator2|, motor l and conductors 23 and 23. Rheostat 31 may be calibrated toread in units of tension rather than units of pre-set coil currentstrength or-loop circuit current strength. Thus the operator may set thearm 38 of rheostat 31 for any given predetermined constant tension onmaterial l2, which setting may be checked during operation of theapparatus by reference to the aforementioned ammeter 25, which thenserves to indicate whether the apparatus is functioning properly.

To summarize, the current regulator 21 is adapted to modify the strengthof field 28 to maintain a constant current output from generator 2|; andthe rheostat 31 is adapted to control the magnitude of the current inthe loop circuit for any given setting. In further illustration, it maybe said that since regulator 21 is always attempting to adjust field 28of generator 2| for a constant armature current, it will do thisregardless of the value of field current and regardless of the value ofgenerator voltage required to produce the constant current. This meansthat, for a given setting of arm 38 of adjustable rheostat 31, thearmature current will be maintained at a constant value through motor I!regardless of the voltage required and regardless of the mill speed orcoiler speed, down to and including zero.

The foregoing apparatus for supplying any predetermined constant currentto motor l5 has been set forth only as an example of a convenientapparatus for providing such constant current. A similar apparatus, ofwhich the above-described apparatus is a modification, will be foundfully set forth in my prior Patent No. 2,043,208.

With constant excitation of field IS, the foregoing system may beemployed to produce any desired predetermined constant torque in thecoiler drive motor l5. As aforementioned, the torque of the coiler motorI5 must be varied to compensate for change in radius of the coil l3 inorder to maintain the predetermined constant tension on the stripmaterial |2.- .The effect of change in radius or build-up of stripmaterial forming coil 3 may be offset by increasing the strength of thefield iii of motor IS. The aforementioned field rheostat l9 has beenprovided for this purpose. A rheostat driving motor 30 is suitablymechanically coupled with rheostat arm 20, and is adapted to move thearm 20 to vary the resistance in circuit with field I6. A photoelectricdevice and associated means, which are novel features of this invention,are employed to automatically change the torque of motor l5 by operatingthe rheostat driving motor 30. Movement of rheostat arm .20 may beeffected in such a manner as to accurately effect the change in torquerequired to maintain constant tension in the strip material, that is,according to changing build-up radius of the strip material on coilerI3. It will now be apparent that if rheostat arm 2|! is properlyadjusted as the build-up radius of coil H on coiler l3 increases, thetorque of motor IE will be accordingly increased to compensate for theincrease in build-up.

The photo-electric build-up compensating system comprises a light sourcegenerally identified by reference numeral 3|, a photo-electric cell 32,and an electrical system associated therewith. Light source 3| may becomprised of any convenient form of lamp or bulb 33, and is preferablyused in conjunction with a parabolic reflector 33 adapted to directsubstantially parallel rays of light across some lateral portion of thebuild-up path of the strip material forming coil l3. Light source 3| maybe conveniently and securely attached to any suitable foundation, as bymeans of a bracket 35. In the form of the invention shown in thedrawing, a beam of substantially parallel light rays 36 is directed pastthe underside of coiler l3 so that one edge of the beam would interceptthe coiler or reel l3 if there were no material thereon, the other edgeof the beam being sufficiently spread downwardly as to pass through thespace to be occupied by a fully wound coil of material on coiler l3. The

but slightly diverging rays of light may be used to accomplish the samepurpose and will magnify the change in radius of the coil I4. The beamof light rays 48 is directed toward the photo-electric cell 42, alsolocated below the pass line of the strip material on the opposite sideof the coiler II from the light source 4I. Placing light source 4I,photo-electric cell 42, and the associated apparatus below the pass lineof the coiler and the mill permits greater freedom of movement on thepart of the operator, without interfering with the operation of theapparatus; but it is obvious that the beam could be disposed above thecoiler or could be directed parallel to the axis of the coiler or at anangle thereto, as may be found desirable.

In more particular description, the photo-electric cell 42, which may beprovided with a suitable shield or other optical device 41 for receivinga small increment of the rays of light 40 and directing them upon thelight-responsive portion of the photo-electric cell 42, is mountedupon'a vertically movable rack 48. Thus the photoelectric cell ismovable across the rays of light 46 in a direction perpendicular theretoand perpendicular to the axis of coiler I3. Other suitable directions ofmovement for photo-electric cell 42 could be chosen if desired. Rack 48is shown diagrammatically as slidable in vertical guides 49 and 50, andis movable in these guides to traverse photo-electric cell 42 over thefull span of the beam of light rays 46. A pinion engages the rack 48 andis adapted to move and locate the rack 48 to bring the photo-electriccell 42 into or out of the unintercepted rays of light beam 46. PinionII is driven by a self-synchronous, tie motor 52 operable as a receiverof electrical impulses from a corresponding selfsynchronous, tiegenerator ll, operable as a transmitter of electrical impulses. Theself-synchronous, tie generator 53 is. mechanically coupled to theaforementionedrheostat drive motor 40. The self-synchronous, tie motor52 and tie generator 53 are devices known in the art,

which are adapted to Operate in exact relation with each other, beingfull electrical equivalents for a mechanical coupling therebetween. Theself-synchronous. tie motor and tie generator are used in thisembodiment of the invention to make it possible to space, or separate,the apparatus for driving rheostat arm 2| away from the photo-electricapparatus, which must be located adjacent the coiler I2. Rotors 54 and55 of tie motor 82 and tie generator ll, respectively, are supplied withalternating current by means of conductors 58 and 51 connecting bothrotors l4 and 55 to power mains La and In, which may be 110 volt, 60cycle, alternating current mains, for example. Leadwii'es'il, 59, and 0connect the stators of tie motor and tie generator 53 for carrying thecontrol currents transmitted by tie generator I3 to the tie motor 52. Itis to be noted at this point that the movement of photoelectric cell 42across the beam of light 46 is directly coordinated with the movement ofrheostat arm 24 by the aforementioned system including the tie generatorand tie motor.

Photo-electric cell 42 is connected to, and associated with a relay boxI by means of lead wires 42 and 48, photo-electric cell 42 and relay boxI comprising one of several standard forms of photo-electric relays.Relay box I is energized by power from mains Ls and L1, supplied throughconductors 84 and ill. The assembly of photo-electric cell 42 and relaybox OI may be a standard photo-electric unit as aforesaid and,therefore, its detailed wiring has not been shown in the drawing.

The driving means for rheostat arm 20 and rack 48 is controlled by thephoto-electric unit through relay box II. The drive motor 40, coupled tothe rheostat arm 20, is preferably a splitseries-field electric motor,and is also coupled to the self -synchronous tie generator 52, asaforesaid. Split-fleld drive motor 40 has two series fields O6 and 61,and is adapted to operate in opposite directions as one or the otherfield, it or I1, is excited. Drive motor 40 is connected throughconductor 68 and resistor 69, if desired for speed control, to thecurrent main L1; it is also connected to the current main 1a through aconductor 10.

In circuit with conductor 10, the second lead to motor 40, is asingle-pole, double-throw contactor switch having a contact member H,operable to send current either through a lead wire 12, a handcontrolled switch I14, and field 81, or through a lead wire 13, a handcontrolled switch 14, and field 86. Contact member 1I may be gravityoperated or spring operated to normally connect to lead wire 12, beingoperable by a coil operated plunger 15 to make contact with lead wire13. Coil operated plunger 15 is operable to move contact member H fromits normal contact with lead wire 12, by means of a coil 18 which may beenergized from relay box 6| by current through lead wires 11 and 1!, tomake contact with lead wire 13, in response to impulses from relay box8| initiated by light impinging upon photo-electric cell 42.Photo-electric cell 42 and relay box 6| are so connected to the coil 1|for contact member 1I that, whenever the light source 4| illuminatescell 42, contact member H is energized to make contact with lead wire13. At this point, if switch 14 is closed, motor 40 will be caused torotate in a direction toward increasing the resistance of rheostat IS.Cell 42 and relay box SI are further related to coil 16 so that,whenever light directed toward cell 42 is intercepted by coil I4 andcell 42 is not illuminated, contact member H is pulled by aspring or bygravity to make normal contact with lead wire 12. At this point, ifswitch I14 is closed, motor 40 will be caused to rotate in a directiontoward decreasing the resistance of rheostat I9. Thus motor 40 will beenergized to run in either one direction or the other, there being no"0!!" position of contact member 1|. The foregoing statement has beenmade with the assumption that switches 14 and I14 have been closed. Theeffect of these latter switches on the operation of the apparatus willbe set forth hereinafter.

The torque-controlling apparatus having been described, its operationmay now be set forth. For simplicity of description, it is first assumedthat'coil I4 is in an initial position as illustrated on the drawing,mechanism and controls for threading strip material I2 upon the coilerI! being omitted since they do not form a necessary part of thisdescription. It is further assumed that rolls I I and II and coiler I3are at rest and that the photoelectric cell 42 is in a dark position,that is, where it is not receiving light from light source 4|; thatcontact member H is in its normal position in contact with lead ,wire12; and that switch I14 is closed. Under these conditions current willflow to the drive motor 40 through series field 61, causing drive motor40 to turn rheostat arm 20 on rheostat IS in a direction to decrease theresistance in circuit with the field 16 of the coiler drive motor l5,thereby increasing the torque developed by coiler motor IS. The rotor 55of the self-synchronous, tie generator 53 is simultaneously turned bythe drive motor 40 and transmits electrical impulses to theself-synchronous, tie motor 52. The tie motor 52 simultaneously rotatespinion 5| in a direction to move rack 48 downwardly. This action movesthe photo-electric cell 42 downwardly into a light position, that is,into unintercepted rays of the light beam 46. The optical device 41associated with the photoelectric cell 42 will be moved into the firstrays of light passing beyond the coiler l3 and under the outer layer ofmaterial on coil l4. At the moment light strikes the photo-electric cell42, the relay box 6| receives impulses from the photo-responsive elementin the photo-electric cell 42. The relay box 6| energizes coil 18,causing contact member 1| to open the circuit going to series field 61of motor 40 through lead wire 12 and to make contact with the lead wire13, closing part of the circuit to field 66 and drive mo- ,tor 40. Atthis point, if the switch 14 in lead wire 13 is open, in the positionshown on the drawing, no further operation of equipment will take placeuntil there is some change in the radius of the coil l4 which, forpresent purposes, has been assumed to be stationary.

The operation 0 e apparatus with switch 14 open, however, is not theonly method of using the equipment illustrated. A second method of usingthe apparatus results if switch 14 has been previously closed before themovement of contact member 1 I, to make contact with lead wire 13. Underthis condition, the drive motor 40 will be immediately reversed torotate in opposite direction, being energized by field 66. The rotationof drive motor 40 in a reverse direction simultaneously decreases thetorque of the coiler drive motor 15 and moves the photo-electric cell 42back out of the light beam 46 into a dark position, whereupon,substantially at the movement of the cell into the dark position, thecoil 16 is de-energized, no current flowing from the relay box SI, andcontact member 1| returns to its normal position in contact with leadwire 12. Upon the closing of contact member 1| upon lead wire 12, theabove-described oscillating cycle will be repeated and will continue.

ferred to as a stop-and-go or continual movement. Simultaneous with themovement of the photo-electric cell 42 will be the movement of rhecstatarm 20 to decrease the resistance afforded by rhecstat It in circuitwith the field lb of the coiler drive motor l5.

If the switch 14 has also been closed and the coiler I3 is in operation,the torque-controlling apparatus will function in a manner similar tothat secondly described above, except that the photo-electric cell 42will have a hunting motion. In other words, the photo-electric cell willbe continuously moved into and out of the edge of the beam of light 46passing beyond the coiler l3 in an oscillating cycle and will follow thebuilt-up, and the interception of light thereby,

with a back and forth motion of small magni-' tude. Rheostat arm 20 willbe moved in accordance with the motion of photo-electric cell 42, but asmall amount of backlash may be left in the couplings to rhecstat arm20, whereby the slight backward movement of photo-electric cell 42 maynot necessarily be transmitted to rheostat arm 20. Further, in thismanner of operating the above-described equipment, when the coil I4 isremoved from coiler l3, the photo-electric cell 42 will automatically betraversed back to its starting position and the' rhecstat arm 2|! willbe likewise turned back to its initial position. However, if the switch14 be left open,-

as in the first described operation wherein the stop-and-go action ofthe photo-electric cell is used, the switch 14 or some other controlmust be closed to return the apparatus to initial position, after acompleted coil l4 has been removed from the coiler l3.

From the foregoing description of a preferred form of theapparatus andtwo methods of its operation, it may be said that, by properly designingthe rheostat l9 and the rhecstat 31, a constant current through thearmature of coiler motor l5, and a-constant tension applied by thecoiler motor l5 may be maintained. These conditions will result in aconstant tension on the material being processed regardless of the millspeed, down to and including a full stop. The behavior of rhecstat I8 issubstantially the same as though the rhecstat arm 20 were mechanicallyoperated by a roller on a fulcrumed arm rid- Up to this point theapparatus has been assumed to be at rest. If coiler I3 is now assumed tobe in motion with the coiler motor [5 developing a preset torquedetermined by a particular setting of arm 38 on rhecstat 31, the radiusof build-up of strip material on coiler I3 will be progressively andcontinuously increasing, though it will be increasing at a decreasingrate. The build-up of strip material on coiler l3 will gradually cutoil;' more and more rays of light in the beam 46, which will requireprogressive movement of rack 48 and rhecstat arm 20 as will now bedescribed.

With the switch 14 open, switch I14 closed, and coiler l3 in operation,the torque-controlling apparatus will function as first described above,

except that the photo-electric cell will be moved until it receiveslight and then will remain at rest until build-up cuts off light. Thecycle will begin again and continue when light is cut off from opticaldevice 41, photo-electric cell 42 being moved in successive,progressive, intermittent movement following the build-up of stripmaterial on coiler I3. This movement may be reing in contact with thecoil [4, the arm being adapted to actuate the rhecstat arm 20 inresponse to build-up of strip material on the coiler. In other words,the rhecstat arm 20 will have a definite position for every outsidediameter of the coil l4.

Before describing the aforementioned preferred embodiment of theinvention and modifications in its operation, it was pointed out thatthe apparatus could function as a back torquecontroliing means for anunwinding reel adapted to maintain tension on the strip material as itenters a mill or other device employing rolls or the like, such as areindicated at l0 and II. The drawing accompanying this specification maybe considered a complete disclosure. not only of the rewind deviceabove-described, but also of an unwind device, or of an apparatusadapted to perform the functions of both an unwind and a rewind device.drawing as representing an unwind device and controlling means therefor,the reference numerals may be descriptive of the same elements of theapparatus with the following changes: reversal of power flow in theelectric drive machines; reversal of potentiometer control forConsidering the 25u-zuo iield 28 by means of the double-throw switch II;and, for stop-and-go movement, opening of switch I" and closing ofswitch ll (switches I4 and H4 reverse their functions in other words).

The strip I! may be considered as moving toward rolls II and II,unwinding from a reel II, and the tension'on strip material I! may beconsidered as eilectuated by regenerative braking in a generator II.Generator I! may be considered as supplying power to a motor II, thecurrent input to motor 2| being controlled by the same devices alreadydescribed, to maintain current at a constant value. Switch 30 isprovided to reverse the eflect of potentiometer tap 38 and resistor 28,so that the strength 01 held ll will be increased upon any tendencytoward strengthening of current in the loop circuit, to providegreater-back electromotive force in motor 2|. Thus the regenerativebraking or back torque of generator I will be constant unless theexcitation of generator I! is varied. The motor 2| may be considered asdriving a generator 22 feeding into power mains L3, L4, and Lo, and thedecreasing amount of back torque required on the coiler It to compensatefor rundown may be effected by the aforedescribed photo-electrictorque-controlling means. The photo-electric control means will beoperated, in the same manner as described, to increase the resistance incircuit with the held it of the generator I! to cause generator I! todevelop less back torque, thereby to compensate for the decreasingradius of unwind coil H. For operation in this manner the movement ofcell 42 and rack 4| will be reversed to follow run-down rather thanbuild-up.

While the invention has been described with respect to a dynamo-electricmachine It coupled to the reel II, which mechanism is adapted tofunction as either an unwind or a rewind reel by mere reversal of thedirection of power flow, the invention is not to be construed as limitedto electrical torque-applying means for the reel It. It is within thescope of the above-described invention-to apply the photo-electrictorquecontrolling means to other known or subsequently developed drivingmeans and braking means, operable by mechanical, hydraulic, or pneumaticmeans and the like. It is pointed out that the photo-electric portion ofthe torquecontrolling device lends itself to various modificationscoming within the scope of the present invention, and the particularform of device described is not to be taken to limit the scope of theinvention. It is c plurality of photo-electric cells associated ith, orindependent "ofroth'er 'optical devices could be used'io perform thefunction r indicatinrchan'gm'radius of c qi l I4, and of adius'tbrfiimplied'thereto by suitable relays, control motors, or otherdevices.

Having thus described and explained my invention and its mode ofoperation, I desire it to be understood that the apparatus described wasselected merely-for the purpose of illustration, and that numerousvariations in the form and arrangement of parts shown and describedherein may be made without departing from the nature and scope of myinvention.

I claim:

1. An apparatus for handling strip material and the like comprising areel, driving means for said reel, means for adjusting the torque onsaid reel, a stationary source 01' radiant energy disposed and adaptedto emit a beam of radiations across said reel, means responsive to radilations impinging thereon from said source disposed to receive and sensea small increment of the radiations of said beam and adapted to havemovement across said beam of radiations to follow change in radius ofmaterial on said reel, means for moving said radiation responsive meansas aforesaid in synchronism with the adiustment of said torque-adjustingmeans, and means connecting said radiation responsive mean and saidtorque-adjusting means, said radiationresponsive means and saidconnecting means being adapted to actuate said torque-adlusting means inresponse to progressive change in interception of the increment ofradiations sensed by said radiation responsive means caused by change inradius oi material on said reel.

2. An apparatus for handling strip material and the like comprising arewind reel, an electric motor operatively connected with said reel, anadjustable current regulator for maintaining a selected constant currentin the armature of said motor, an adjustable rheostat for varying thestrength of the held of said motor, driving means for said rheostat, astationary source oi light disposed and adapted to emit a beam ofsubstantially parallel light rays across a space to be occupied bymaterial on said reel, photoelectric means disposed to receive and sensea small increment of the rays of said beam and adapted to have movementacross said beam 0! light rays to follow build-up of material on saidreel, means for moving said photo-electric means as aforesaid insynchronism. with the adjustment of said rheostat through said drivingmeans therefor, and electrical means connecting said photo-electricmeans and saidrheostat driving means, said photo-electric means andelectrical connecting means being adapted to actuate said rheostatdriving means in response to progressive change in interceptionof theincrement of light rays sensed by said photo-electric means caused bybuild-up of strip material on said reel.

3. An apparatus for handling strip material and the like comprising anunwind reel, an electric generator operatively connected with said reel,an adjustable current regulator for maintaining a selected constantcurrent in the armature of said generator, an adjustable rheostat forvarying the strength of the field of said generator, driving means forsaid rheostat, a stationary source of light disposed and adapted to emita beam of substantially parallel light rays across a space to beoccupied by material on said reel, photo-electric means disposed toreceive and sense a small increment of the rays of said beam and adaptedto have movement across said beam of light rays to follow run-down ofmaterial on said reel, means for moving said photo-electric means asaforesaid in synchronism with the adjustment of said rheostat throughsaid driving means therefor, and electrical means connecting saidphoto-electric means and said rheostat driving means, saidphoto-electric means and said electrical connecting means being adaptedto actuate said rheostat driving means in response to progressive changein interception of the increment of light rays sensed by saidphoto-electric means caused by run-down of material on said reel.

4. An apparatus for handling strip material and the like comprising arewind reel, driving means for said reel, means for adjusting the torqueon said reel. reversible driving means for l-JU IIIIII Il-II

